6.5 Sensor Controller
The Sensor Controller contains circuitry that can be selectively enabled in standby mode. The peripherals in this domain may be controlled by the Sensor Controller Engine, which is a proprietary power-optimized CPU. This CPU can read and monitor sensors or perform other tasks autonomously, thereby significantly reducing power consumption and offloading the main Cortex-M3 CPU.
The Sensor Controller is set up using a PC-based configuration tool, called Sensor Controller Studio, and typical use cases may be (but are not limited to):
- Analog sensors using integrated ADC
- Digital sensors using GPIOs and bit-banged I2C or SPI
- UART communication for sensor reading or debugging
- Capacitive sensing
- Waveform generation
- Pulse counting
- Keyboard scan
- Quadrature decoder for polling rotation sensors
- Oscillator calibration
The peripherals in the Sensor Controller include the following:
- The low-power clocked comparator can be used to wake the device from any state in which the comparator is active. A configurable internal reference can be used with the comparator. The output of the comparator can also be used to trigger an interrupt or the ADC.
- Capacitive sensing functionality is implemented through the use of a constant current source, a time-to-digital converter, and a comparator. The continuous time comparator in this block can also be used as a higher-accuracy alternative to the low-power clocked comparator. The Sensor Controller will take care of baseline tracking, hysteresis, filtering and other related functions.
- The ADC is a 12-bit, 200-ksamples/s ADC with eight inputs and a built-in voltage reference. The ADC can be triggered by many different sources, including timers, I/O pins, software, the analog comparator, and the RTC.
- The Sensor Controller also includes a SPI/I2C digital interface.
- The analog modules can be connected to up to eight different GPIOs.
The peripherals in the Sensor Controller can also be controlled from the main application processor.
Table 6-1 lists the GPIOs that are connected to the Sensor Controller.
Table 6-1 GPIOs Connected to the Sensor Controller(1)
ANALOG CAPABLE |
16.9 × 11 MOH DIO NUMBER |
Y |
14 |
Y |
13 |
Y |
12 |
Y |
11 |
Y |
9 |
Y |
10 |
Y |
8 |
Y |
7 |
N |
4 |
N |
3 |
N |
2 |
N |
1 |
N |
0 |
(1) Up to 13 pins can be connected to the Sensor Controller. Up to eight of these pins can be connected to analog modules